Engine is now in a running state and can also sustain itself right side up now - running quite well - vid attached https://www.youtube.com/watch?v=M-DI3TNrwx4

Please post / tag your makes!

18/1/21 Made some minor changes for ease of assembly and smoothed edging. Piston slightly adjusted for better valve seal and release

9/4/20 Reverted to single valve seal and enlarged piston nipple which increased RPM after finding the best fit, changed main crankshaft bolt to M4 for durability

8/2/20 Improved strength of conrod and allowed fitment of two bearings on each end, keyed crankshaft and flywheel plus general fitment improvements allowing higher RPM and power

31/1/20 More updates to valve ring fitment to hold better, added piston ring for better sealing and fine tuned to make it run efficiently with more power

12/1/20 Fine adjustments to fit and prepping for piston rubber ring setup, smoothed idle out by making slight changes to valve

3/1/20 Slight adjustments to valve delay using piston nipple length and closed the gap at TDC, adjusted exhaust height, crankshaft strengthened and other small changes

1/1/20 Complete re-design of valve system, spring and printed valve is no longer being used and a new chamber exists for pressurized air. Standard plastic 6mm BB and a delayed re-seal setup is being used, still testing but engine runs!!! Will list new seal in requirements, this has shown to be a tight seal and pretty efficient

23/12/19 Multiple changes to smooth out and strengthen design, tighten clearances plus make it easier to print, updated flywheel to stop any crankshaft movement and added a prop spacer

21/11/19 Updating mounting points for better O-ring fit and general improvements

13/10/19 Lots of overall changes, smoothing and fitment etc with a flywheel allowing prop usage

19/9/19 Adjusted mounting locations to lock down bearings better, slightly tighter thread holes and other small fixes

15/9/19 Fixes to piston and conrod, loosened m3 fit for top and bottom end and changed air nipple

This is my attempt at designing and drawing a working and sizeable compressed air engine that is mostly printable with few external parts required.

Feel free to try it out and give me feed back, note it's a work in progress and I'm still working out the kinks.

Use common sense for orientation, supports should not be required depending on your printers ability.

Bellow can be found easily on https://aliexpress.com

Required:

2x 608 universal skateboard bearings (crankshaft bearings)
https://www.aliexpress.com/item/33051895647.html?spm=a2g0o.productlist.0.0.f668433ezCGFwU&algo_pvid=b2c6d0fd-5d5b-47a6-94b1-f57ca5a26d32&algo_expid=b2c6d0fd-5d5b-47a6-94b1-f57ca5a26d32-3&btsid=a7104a1b-d334-4ad3-8f70-ca2f6ce4ce47&ws_ab_test=searchweb0_0,searchweb201602_6,searchweb201603_53

4x 682ZZ 2x5x2mm bearings (conrod bearings)
https://www.aliexpress.com/item/32862636969.html?spm=a2g0s.9042311.0.0.27424c4dIet80A

1x 2mm thick lengthy steel rod (cut as needed, for piston pin and conrod crank pin)
https://www.aliexpress.com/item/32297671032.html?spm=a2g0s.9042311.0.0.27424c4dIet80A

2x 35mm x1mm OD O-Ring (head seals)
https://www.aliexpress.com/item/32844105437.html?spm=a2g0s.9042311.0.0.27424c4dYMR0Mb

1x 5mm x1mm OD O-Ring (new BB valve seal)
https://www.aliexpress.com/item/32725251085.html?spm=a2g0s.9042311.0.0.27424c4dIet80A

1x 28mm x1mm OD O-Ring (Piston ring)
https://www.aliexpress.com/item/32844105437.html?spm=a2g0s.9042311.0.0.27424c4dI2J7fy

10x M3x20mm bolts (for fusing points)
https://www.aliexpress.com/item/33003801934.html?spm=a2g0s.9042311.0.0.27424c4dIet80A

1x M4x70 or shorter for crank shaft prop mounting (reinforces crankshaft, 70 works best)
https://www.aliexpress.com/item/32966157667.html?spm=a2g0s.9042311.0.0.27424c4dDC3vpk

1x Standard 6mm air soft BB (new valve)

1x Some form of propeller (shaft is just under 8mm in diameter) or spin-able weight to act as a true flywheel

I'll add other requirements if needed as I print and test - I am by no means an expert CAD user so I'm still learning as I go.

Thanks for looking!

Prusa

I3 MK3S

No

No

0.2

25%